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Journal of Applied Physiology... Mar 2009Mental fatigue is a psychobiological state caused by prolonged periods of demanding cognitive activity. Although the impact of mental fatigue on cognitive and skilled...
Mental fatigue is a psychobiological state caused by prolonged periods of demanding cognitive activity. Although the impact of mental fatigue on cognitive and skilled performance is well known, its effect on physical performance has not been thoroughly investigated. In this randomized crossover study, 16 subjects cycled to exhaustion at 80% of their peak power output after 90 min of a demanding cognitive task (mental fatigue) or 90 min of watching emotionally neutral documentaries (control). After experimental treatment, a mood questionnaire revealed a state of mental fatigue (P = 0.005) that significantly reduced time to exhaustion (640 +/- 316 s) compared with the control condition (754 +/- 339 s) (P = 0.003). This negative effect was not mediated by cardiorespiratory and musculoenergetic factors as physiological responses to intense exercise remained largely unaffected. Self-reported success and intrinsic motivation related to the physical task were also unaffected by prior cognitive activity. However, mentally fatigued subjects rated perception of effort during exercise to be significantly higher compared with the control condition (P = 0.007). As ratings of perceived exertion increased similarly over time in both conditions (P < 0.001), mentally fatigued subjects reached their maximal level of perceived exertion and disengaged from the physical task earlier than in the control condition. In conclusion, our study provides experimental evidence that mental fatigue limits exercise tolerance in humans through higher perception of effort rather than cardiorespiratory and musculoenergetic mechanisms. Future research in this area should investigate the common neurocognitive resources shared by physical and mental activity.
Topics: Adult; Affect; Female; Humans; Male; Mental Fatigue; Perceptual Distortion; Physical Exertion; Time Factors
PubMed: 19131473
DOI: 10.1152/japplphysiol.91324.2008 -
Nature Communications Nov 2023Introspective agents can recognize the extent to which their internal perceptual experiences deviate from the actual states of the external world. This ability, also...
Introspective agents can recognize the extent to which their internal perceptual experiences deviate from the actual states of the external world. This ability, also known as insight, is critically required for reality testing and is impaired in psychosis, yet little is known about its cognitive underpinnings. We develop a Bayesian modeling framework and a psychophysics paradigm to quantitatively characterize this type of insight while people experience a motion after-effect illusion. People can incorporate knowledge about the illusion into their decisions when judging the actual direction of a motion stimulus, compensating for the illusion (and often overcompensating). Furthermore, confidence, reaction-time, and pupil-dilation data all show signatures consistent with inferential adjustments in the Bayesian insight model. Our results suggest that people can question the veracity of what they see by making insightful inferences that incorporate introspective knowledge about internal distortions.
Topics: Humans; Perceptual Distortion; Illusions; Bayes Theorem; Psychophysics; Psychotic Disorders; Motion Perception
PubMed: 38030601
DOI: 10.1038/s41467-023-42813-2 -
Frontiers in Neuroscience 2021Although animal studies and studies on Parkinson's disease (PD) suggest that dopamine deficiency slows the pace of the internal clock, which is corrected by dopaminergic...
Although animal studies and studies on Parkinson's disease (PD) suggest that dopamine deficiency slows the pace of the internal clock, which is corrected by dopaminergic medication, timing deficits in parkinsonism remain to be characterized with diverse findings. Here we studied patients with PD and progressive supranuclear palsy (PSP), 3-4 h after drug intake, and normal age-matched subjects. We contrasted perceptual (temporal bisection, duration comparison) and motor timing tasks (time production/reproduction) in supra- and sub-second time domains, and automatic versus cognitive/short-term memory-related tasks. Subjects were allowed to count during supra-second production and reproduction tasks. In the time production task, linearly correlating the produced time with the instructed time showed that the "subjective sense" of 1 s is slightly longer in PD and shorter in PSP than in normals. This was superposed on a prominent trend of underestimation of longer (supra-second) durations, common to all groups, suggesting that the pace of the internal clock changed from fast to slow as time went by. In the time reproduction task, PD and, more prominently, PSP patients over-reproduced shorter durations and under-reproduced longer durations at extremes of the time range studied, with intermediate durations reproduced veridically, with a shallower slope of linear correlation between the presented and produced time. In the duration comparison task, PD patients overestimated the second presented duration relative to the first with shorter but not longer standard durations. In the bisection task, PD and PSP patients estimated the bisection point (BP50) between the two supra-second but not sub-second standards to be longer than normal subjects. Thus, perceptual timing tasks showed changes in opposite directions to motor timing tasks: underestimating shorter durations and overestimating longer durations. In PD, correlation of the mini-mental state examination score with supra-second BP50 and the slope of linear correlation in the reproduction task suggested involvement of short-term memory in these tasks. Dopamine deficiency didn't correlate significantly with timing performances, suggesting that the slowed clock hypothesis cannot explain the entire results. Timing performance in PD may be determined by complex interactions among time scales on the motor and sensory sides, and by their distortion in memory.
PubMed: 33815049
DOI: 10.3389/fnins.2021.648814 -
Scientific Reports Oct 2020Humans interact in groups through various perception and action channels. The continuity of interaction despite a transient loss of perceptual contact often exists and...
Humans interact in groups through various perception and action channels. The continuity of interaction despite a transient loss of perceptual contact often exists and contributes to goal achievement. Here, we study the dynamics of this continuity, in two experiments involving groups of participants ([Formula: see text]) synchronizing their movements in space and in time. We show that behavioural unison can be maintained after perceptual contact has been lost, for about 7s. Agent similarity and spatial configuration in the group modulated synchronization performance, differently so when perceptual interaction was present or when it was memorized. Modelling these data through a network of oscillators enabled us to clarify the double origin of this memory effect, of individual and social nature. These results shed new light into why humans continue to move in unison after perceptual interruption, and are consequential for a wide variety of applications at work, in art and in sport.
Topics: Adult; Female; Humans; Male; Memory; Movement; Perceptual Distortion; Space Perception; Visual Perception; Young Adult
PubMed: 33093528
DOI: 10.1038/s41598-020-74914-z -
PloS One 2022Deep neural networks have shown great improvements in low-dose computed tomography (CT) denoising. Early algorithms were primarily optimized to obtain an accurate image...
Deep neural networks have shown great improvements in low-dose computed tomography (CT) denoising. Early algorithms were primarily optimized to obtain an accurate image with low distortion between the denoised image and reference full-dose image at the cost of yielding an overly smoothed unrealistic CT image. Recent research has sought to preserve the fine details of denoised images with high perceptual quality, which has been accompanied by a decrease in objective quality due to a trade-off between perceptual quality and distortion. We pursue a network that can generate accurate and realistic CT images with high objective and perceptual quality within one network, achieving a better perception-distortion trade-off. To achieve this goal, we propose a stationary wavelet transform-assisted network employing the characteristics of high- and low-frequency domains of the wavelet transform and frequency subband-specific losses defined in the wavelet domain. We first introduce a stationary wavelet transform for the network training procedure. Then, we train the network using objective loss functions defined for high- and low-frequency domains to enhance the objective quality of the denoised CT image. With this network design, we train the network again after replacing the objective loss functions with perceptual loss functions in high- and low-frequency domains. As a result, we acquired denoised CT images with high perceptual quality using this strategy while minimizing the objective quality loss. We evaluated our algorithms on the phantom and clinical images, and the quantitative and qualitative results indicate that ours outperform the existing state-of-the-art algorithms in terms of objective and perceptual quality.
Topics: Algorithms; Image Processing, Computer-Assisted; Neural Networks, Computer; Radiation Dosage; Signal-To-Noise Ratio; Tomography, X-Ray Computed; Wavelet Analysis
PubMed: 36084002
DOI: 10.1371/journal.pone.0274308 -
Frontiers in Sports and Active Living 2023
PubMed: 36814895
DOI: 10.3389/fspor.2023.1138516 -
Frontiers in Psychology 2022Previous research has contrasted fleeting erroneous experiences of familiarity with equally convincing, and often more stubborn erroneous experiences of remembering....
Previous research has contrasted fleeting erroneous experiences of familiarity with equally convincing, and often more stubborn erroneous experiences of remembering. While a subset of the former category may present as nonpathological "déjà vu," the latter, termed "déjà vécu" can categorize a delusion-like confabulatory phenomenon first described in elderly dementia patients. Leading explanations for this experience include the dual process view, in which erroneous familiarity and erroneous recollection are elicited by inappropriate activation of the parahippocampal cortex and the hippocampus, respectively, and the more popular encoding-as-retrieval explanation in which normal memory encoding processes are falsely flagged and interpreted as memory retrieval. This paper presents a novel understanding of this recollective confabulation that builds on the encoding-as-retrieval hypothesis but more adequately accounts for the co-occurrence of persistent déjà vécu with both perceptual novelty and memory impairment, the latter of which occurs not only in progressive dementia but also in transient epileptic amnesia (TEA) and psychosis. It makes use of the growing interdisciplinary understanding of the fluidity of time and posits that the functioning of memory and the perception of novelty, long known to influence the subjective experience of time, may have a more fundamental effect on the flow of time.
PubMed: 35967717
DOI: 10.3389/fpsyg.2022.794683 -
Journal of Speech, Language, and... Feb 2012This review article provides a theoretical overview of the characteristics of perceptual learning, reviews perceptual learning studies that pertain to dysarthric... (Review)
Review
PURPOSE
This review article provides a theoretical overview of the characteristics of perceptual learning, reviews perceptual learning studies that pertain to dysarthric populations, and identifies directions for future research that consider the application of perceptual learning to the management of dysarthria.
METHOD
A critical review of the literature was conducted that summarized and synthesized previously published research in the area of perceptual learning with atypical speech. Literature related to perceptual learning of neurologically degraded speech was emphasized with the aim of identifying key directions for future research with this population.
CONCLUSIONS
Familiarization with unfamiliar or ambiguous speech signals can facilitate perceptual learning of that same speech signal. There is a small but growing body of evidence that perceptual learning also occurs for listeners familiarized with dysarthric speech. Perceptual learning of the dysarthric signal is both theoretically and clinically significant. In order to establish the efficacy of exploiting perceptual learning paradigms for rehabilitative gain in dysarthria management, research is required to build on existing empirical evidence and develop a theoretical framework for learning to better recognize neurologically degraded speech.
Topics: Adaptation, Psychological; Discrimination Learning; Dysarthria; Humans; Learning; Perceptual Distortion; Speech Intelligibility; Speech Perception
PubMed: 22199185
DOI: 10.1044/1092-4388(2011/10-0349) -
European Review For Medical and... Mar 2022COVID-19 has been associated with a wide range of quantitative and qualitative disorders of smell, including hyposmia/anosmia, parosmia, and phantosmia; however, no...
OBJECTIVE
COVID-19 has been associated with a wide range of quantitative and qualitative disorders of smell, including hyposmia/anosmia, parosmia, and phantosmia; however, no reports to date have reported hyperosmia as a sequela of SARS-CoV-2 infection.
PATIENTS AND METHODS
We present two cases of subjective hyperosmia in a South Tyrolean Alps family, occurring within days after recovery from SARS-CoV-2 infection with transient anosmia.
RESULTS
The subjects, a mother and son, exhibited subjective hyperosmia despite normal objective olfactory testing. During independent assessments, the severity of hyperosmia and specific odors affected were highly correlated, consistent with shared genetic and environmental factors. In contrast, two other family members with COVID-19 had no perceptual distortion and normal recovery of smell.
CONCLUSIONS
Subjective hyperosmia after COVID-19 infection exhibited striking similarity in two affected family members, suggesting interaction of environment, genetics, and perception.
Topics: COVID-19; Female; Humans; Mothers; Olfaction Disorders; Perception; SARS-CoV-2; Smell
PubMed: 35363370
DOI: 10.26355/eurrev_202203_28368 -
Visual Cognition Jan 2021Studies suggest looming motion represents a special class of attentional capture stimulus due to behavioral urgency: the need to act upon objects moving toward us in an...
Studies suggest looming motion represents a special class of attentional capture stimulus due to behavioral urgency: the need to act upon objects moving toward us in an environment. In particular, one theory suggests that faster reaction times to targets cued by looming relative to receding motion are driven by post-attentional, motor-priming processes beyond the attentional capture effects seen with other stimulus qualities such as color pop-out. The present study tested this theory using a relative size judgment task where targets were pre-cued by looming and receding optic flow fields. Results show systematic increases in the perceived size of targets that were cued by looming flow fields, consistent with previous attentional capture studies using onset cues. These results challenge theories attributing behavioral changes from looming motion to motor-priming alone.
PubMed: 34712098
DOI: 10.1080/13506285.2021.1874583